Routing Engine: CheckConnectorRestrictions parameter is non-default

[This topic is intended to address a specific issue called out by the Exchange Server Analyzer Tool. You should apply it only to systems that have had the Exchange Server Analyzer Tool run against them and are experiencing that specific issue. The Exchange Server Analyzer Tool, available as a free download, remotely collects configuration data from each server in the topology and automatically analyzes the data. The resulting report details important configuration issues, potential problems, and nondefault product settings. By following these recommendations, you can achieve better performance, scalability, reliability, and uptime. For more information about the tool or to download the latest versions, see "Microsoft Exchange Analyzers" at]  

Topic Last Modified: 2005-11-18

The Microsoft® Exchange Server Analyzer Tool reads the following registry entry to determine whether Simple Mail Transfer Protocol (SMTP) connector routing logic has been modified from its default setting:


If the Exchange Server Analyzer finds that the CheckConnectorRestrictions registry key is present and configured with a value greater than 0, a non-default configuration message is displayed.

The CheckConnectorRestrictions registry entry is a custom configuration setting for Exchange Server that enables restriction checking on the Exchange bridgehead server that is the source for the connector that is being checked. By default, connector restriction checking is turned off because it can significantly affect performance, notably in configurations that use many distribution groups. Restrictions will be checked for each message sent to each member of each distribution group that passes through the system. If restrictions are specified but this registry entry does not exist, restriction checking will not be performed.

This article contains information about editing the registry. Before you edit the registry, make sure you understand how to restore the registry if a problem occurs. For information about how to restore the registry, view the "Restore the Registry" Help topic in Regedit.exe or Regedt32.exe.

  1. Open a registry editor, such as Regedit.exe or Regedt32.exe.

  2. Navigate to: HKLM\System\CurrentControlSet\Services\RESvc\Parameters

  3. Delete the CheckConnectorRestrictions registry key.

  4. Close the registry editor.

  5. Restart the IIS Admin Service.

  6. On the connector's Delivery Restrictions tab, re-enable the restriction option.

Before you edit the registry, and for information about how to edit the registry, see Microsoft Knowledge Base article 256986, "Description of the Microsoft Windows Registry" (

For more information about the CheckConnectorRestrictions registry value, see Knowledge Base article 277872, "XCON: Connector Delivery Restrictions May Not Work Correctly" (